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Method for preparing 2,3-dihydroxybenzaldehyde by removing methyl of o-vanillin

A technology of dihydroxybenzaldehyde and o-vanillin, which is applied to the preparation of carbon-based compounds, the preparation of organic compounds, chemical instruments and methods, etc., and can solve the problems of low yield, high preparation cost, and difficulty in industrialized production , to achieve the effect of simple reaction purification operation, wide source and convenient storage

Active Publication Date: 2018-11-16
美迪森(荆门)生物医药科技有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First of all, boron tribromide is expensive, the preparation cost is high, and it is difficult to realize industrial production; secondly, the yield of hydrogen bromide demethylation is relatively low, and the operation is inconvenient
[0004] Aluminum trichloride is also a commonly used demethylation reagent. For example, Lange developed a method for removing o-hydroxyanisole, using aluminum trichloride-pyridine system to remove the methylation of vanillin in halogenated alkanes or aromatics. group (US3256336), but this method cannot be used for the demethylation reaction of o-vanillin (The Journal of Organic Chemistry 1962,27,2037-2039)
[0005] In addition, the reagent system of the combination of aluminum triiodide and various Lewis bases is also used to remove the methyl group of o-vanillin, such as CN106278825A discloses a method for cracking ether bonds with aluminum triiodide-pyridine, and CN106866377A discloses A method for cracking ether bonds with aluminum triiodide-carbodiimide is disclosed, and CN107473916 discloses a method for cracking ether bonds with aluminum triiodide-inorganic bases or metal oxides, although these three methods can be used to remove adjacent The methyl group of vanillin was used to prepare 2,3-dihydroxybenzaldehyde, but the yields of these three methods were not high

Method used

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  • Method for preparing 2,3-dihydroxybenzaldehyde by removing methyl of o-vanillin

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Experimental program
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Effect test

Embodiment 1

[0020]

[0021] Acetonitrile (40ml), aluminum chloride (0.804g, 6.03mmol, 1.1eq), NaI (2.464g, 16.44mmol, 3.0eq) and o-vanillin (0.417g, 2.74mmol) were added to a 100ml eggplant-shaped flask ), heated to 80°C, stopped stirring after 18 hours of reaction, added 2mol / L dilute hydrochloric acid (10ml) to the eggplant-shaped bottle after cooling to room temperature to acidify, extracted with ethyl acetate (50ml×3), combined the organic phases, First wash with a saturated aqueous solution of sodium thiosulfate (10ml), then wash with saturated brine (10ml), dry over anhydrous magnesium sulfate, filter, and the filtrate is evaporated to dryness with a rotary evaporator, and the residue is subjected to flash column chromatography (eluent Purified by ethyl acetate / petroleum ether=1:4, volume ratio) to obtain 0.322g of 2,3-dimethoxybenzaldehyde (yellow solid, yield 85%).

[0022] R f =0.58 (petroleum ether / ethyl acetate=1:3), mp106-108°C.

[0023] 1 H NMR(400MHz,DMSO-d6)δ10.22(s,1...

Embodiment 2

[0025] Add acetonitrile (40ml), aluminum chloride (0.752g, 5.64mmol, 1.1eq), NaI (2.305g, 15.38mmol, 3.0eq) and o-vanillin (0.780g, 5.13mmol) to a 100ml eggplant-shaped flask ), heated to 80°C, stopped stirring after 18 hours of reaction, added 2mol / L dilute hydrochloric acid (10ml) to the eggplant-shaped bottle after cooling to room temperature to acidify, extracted with ethyl acetate (50ml×3), combined the organic phases, First wash with a saturated aqueous solution of sodium thiosulfate (10ml), then wash with saturated brine (10ml), dry over anhydrous magnesium sulfate, filter, and the filtrate is evaporated to dryness with a rotary evaporator, and the residue is subjected to flash column chromatography (eluent Ethyl acetate / petroleum ether=1:4, volume ratio) was purified to obtain 0.620 g of 2,3-dimethoxybenzaldehyde (yellow solid, yield 87%).

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Abstract

The invention discloses a method for preparing 2,3-dihydroxybenzaldehyde by removing methyl of o-vanillin. The method comprises the following steps: in an organic solvent, in the presence of aluminumtrichloride and an iodide, the o-vanillin is subjected to an ether bond cleavage reaction at temperature of -20 DEG C to reflux temperature to form the 2,3-dihydroxybenzaldehyde. The method disclosedby the invention has mild conditions, is simple to operate and has a high yield.

Description

Background technique [0001] The invention relates to the technical field of intermediate synthesis of medicines and chemical raw materials, in particular to a method for preparing 2,3-dihydroxybenzaldehyde by removing the methyl group of o-vanillin. Background technique [0002] 2,3-Dihydroxybenzaldehyde is an important chemical intermediate, such as a key intermediate 2,2-difluoro-1,3-benzodioxol that can be used to prepare the insecticide fludioxonil -4-formaldehyde (CN106699722), and an important raw material for the synthesis of 3'-formyl benzocrown intermediate 3'-formyl benzocrown derivatives (Journal of Zhengzhou Institute of Light Industry 1995, 10, 61-62). [0003] 2,3-Dihydroxybenzaldehyde can be obtained by demethylation of o-vanillin. For example, Potisek et al. reported a preparation of 2,3-dihydroxybenzaldehyde by demethylation of o-vanillin with boron tribromide in dichloromethane. -The method of dihydroxybenzaldehyde (Journal of the American Chemical Socie...

Claims

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Application Information

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IPC IPC(8): C07C45/64C07C47/565
CPCC07C45/64C07C47/565
Inventor 桑大永涂小东田娟
Owner 美迪森(荆门)生物医药科技有限公司
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